Default value constants are created only call uses them

tests/compiler/dart2js/equivalence/check_functions.dart

 // Copyright (c) 2017, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 /// Equivalence test functions for data objects.
 
 library dart2js.equivalence.functions;
 
 import 'package:expect/expect.dart';
 import 'package:compiler/src/common/resolution.dart';
@@ skipping 818 matching lines @@
 
   checkSets(
       worldBuilder1.allReferencedStaticFields,
       worldBuilder2.allReferencedStaticFields,
       "Directly instantiated classes mismatch",
       elementEquivalence,
       verbose: verbose);
   checkSets(worldBuilder1.closurizedMembers, worldBuilder2.closurizedMembers,
       "closurizedMembers", elementEquivalence,
       verbose: verbose);
+
   checkSets(worldBuilder1.processedClasses, worldBuilder2.processedClasses,
       "processedClasses", elementEquivalence,
       verbose: verbose);
+
   checkSets(
       worldBuilder1.methodsNeedingSuperGetter,
       worldBuilder2.methodsNeedingSuperGetter,
       "methodsNeedingSuperGetter",
       elementEquivalence,
       verbose: verbose);
   checkSets(
       worldBuilder1.staticFunctionsNeedingGetter,
       worldBuilder2.staticFunctionsNeedingGetter,
       "staticFunctionsNeedingGetter",
@@ skipping 322 matching lines @@
         print('  ${js.nodeToString(node1)}');
         print('  ${js.nodeToString(node2)}');
       }
       return expectedValue == label2;
     } else {
       labelsMap[label1] = label2;
       return true;
     }
   }
 }